Field of the Invention
This invention relates to prostheses used at locations where adjacent bones articulate and, more particularly, to a prosthesis with cooperating assemblies that can be reconfigured utilizing interchangeable parts.
Background Art
Prostheses are used at many different anatomical locations. Typically, a prosthesis will be made up of separate assemblies secured to adjacent, articulating bones. The separate assemblies have cooperating surfaces that guide relative movement between the bones and are configured to permit, as much as possible, a natural range of motion for a patient's limbs.
Designers of prosthetic devices are driven by a number of different criteria. While comfortable movement in a full range of motion and durability are always overriding objectives in the design process, cost and adaptability of prostheses at each site are also significant considerations. Adaptability relates generally to dimensional variations and material selection, which ideally may be changed during procedures to optimize performance.
It is known to construct the separate assemblies attached to the respective bones from multiple pieces, which allows different materials to be utilized to exploit their particular properties. For example, cooperating assemblies may incorporate one or more components that are non-metal to define surfaces that guide movement between the associated bones. The material defining these surfaces may not have the integrity to facilitate mounting of the prosthesis assemblies to adjacent bones, and thus metal materials are commonly used for this purpose. Joinder of the metal and non-metal components is commonly effected on a permanent basis. As a result, it may be necessary to keep on hand a significant number of prostheses with different configurations to allow them to be selected as a procedure is being performed.
The inventor herein is not aware of any existing prosthesis that allows metal and non-metal parts thereof to be joined releasably in a manner whereby components defining guide surfaces can be readily and practically interchanged to optimize a configuration during the performance of a procedure to implant the prosthesis.
Another limitation associated with these assemblies is the manner in which metal and non-metal parts, or for that matter like composition components, are held together. One common construction utilizes a truncated conical projection on one part of the assembly that fits in a complementary receptacle in another part of the assembly. It is difficult to maintain precise tolerances between the projections and recesses, as a result of which the projections may penetrate the recesses to different depths, whereby the effective overall dimension of the resulting assembly may be only imprecisely predictable. This may result in either tensioned or loose prosthetic connections, which are both detrimental conditions.
The industry continues to seek improved alternative designs that focus on the above design criteria and objectives.